1. Field of the Invention
The invention relates to machines that are used in the making of rubber mixtures.
2. Description of the Related Art
Most of the raw materials used in the rubber industry are solids which exhibit very irregular physical properties (balls of latex, isoprene plates, pellets of additives, powdered carbon black) and their unit masses, for example, vary from about a hundred kilograms to a few micrograms. Before being able to shape these products with accuracy, it is necessary to mix them thoroughly and make them plastic. These operations are successively performed in mixing mills of two types: (1) internal mixers which are closed and where two rotors having complementary shapes mix the rubbers and their fillers (such as carbon black); and (2) roller mixing mills consisting of rotating cylinders with parallel axes, between which the mixtures of products are made to pass several times in succession to homogenize them and change their physical properties (rheology, elasticity, etc.).
When the mixtures get to roller mixing mills, they must be rapidly cooled. Further, the material temperature must be regulated during the homogenization process.
The cylinders of current roller mixing mills are bulky parts which, with or without a central channel, can weigh 7 tons. Their length including journals exceeds 2 meters, and their diameter is on the order of 700 mm. The cylinders have numerous longitudinal channels (parallel to the cylinder axis) drilled from end to end and connected at their ends (see for example patent DE 23 15 669) to make possible a circulation of the temperature regulating liquid from one of the journals.